The present application relates generally to a control system for a machine with a dual path electronically controlled hydrostatic transmission. The present application relates more specifically to controlling the engine load of a machine with a dual path electronically controlled hydrostatic transmission.
One type of machine with a dual path electronically controlled hydrostatic transmission or a dual path electro-hydraulic transmission can be a crawler-tractor such as a bulldozer. “Bulldozers” or “dozers,” as those terms may be used herein, refer to crawler-tractors that are equipped with a blade for scraping the ground or pushing material along the ground. The blade is pivotally connected to the crawler-tractor chassis such that it can pivot up and down. Blade controls are provided to the operator in the cab of the vehicle to permit the operator to raise and lower the blade with respect to the chassis of the crawler-tractor. One of the most common uses for blades on bulldozers is to level or otherwise contour the ground for the construction of houses, buildings, parking lots, and roads.
The dual path electronically controlled hydrostatic transmission can be used for the propulsion and steering of the bulldozer. Machines with dual path electronically controlled hydrostatic transmissions and/or implement systems, such as the bulldozer or other crawler-tractor, are often used for heavy duty operations including push-pull operations, lift-lower operations and/or digging operations. The load carrying capacity of these machines can be increased by managing the available power from the engine. In the absence of a good load management system, the engine may stall during high load conditions such as when performing heavy duty operations, climbing up-hill at high machine speeds or when performing many other similar types of operations.
Therefore, what is needed is a control system to efficiently manage engine load by controlling pump and motor displacements of a machine with a dual path electronically controlled hydrostatic transmission to prevent the engine from stalling.